Semiconductor device and method of forming insulating layer around semiconductor die

ABSTRACT

A plurality of semiconductor die is mounted to a temporary carrier. An encapsulant is deposited over the semiconductor die and carrier. A portion of the encapsulant is designated as a saw street between the die, and a portion of the encapsulant is designated as a substrate edge around a perimeter of the encapsulant. The carrier is removed. A first insulating layer is formed over the die, saw street, and substrate edge. A first conductive layer is formed over the first insulating layer. A second insulating layer is formed over the first conductive layer and first insulating layer. The encapsulant is singulated through the first insulating layer and saw street to separate the semiconductor die. A channel or net pattern can be formed in the first insulating layer on opposing sides of the saw street, or the first insulating layer covers the entire saw street and molding area around the semiconductor die.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and,more particularly, to a semiconductor device and method of forming aninsulating layer around semiconductor die.

BACKGROUND OF THE INVENTION

Semiconductor devices are commonly found in modern electronic products.Semiconductor devices vary in the number and density of electricalcomponents. Discrete semiconductor devices generally contain one type ofelectrical component, e.g., light emitting diode (LED), small signaltransistor, resistor, capacitor, inductor, and power metal oxidesemiconductor field effect transistor (MOSFET). Integrated semiconductordevices typically contain hundreds to millions of electrical components.Examples of integrated semiconductor devices include microcontrollers,microprocessors, charged-coupled devices (CCDs), solar cells, anddigital micro-mirror devices (DMDs).

Semiconductor devices perform a wide range of functions such ashigh-speed calculations, transmitting and receiving electromagneticsignals, controlling electronic devices, transforming sunlight toelectricity, and creating visual projections for television displays.Semiconductor devices are found in the fields of entertainment,communications, power conversion, networks, computers, and consumerproducts. Semiconductor devices are also found in military applications,aviation, automotive, industrial controllers, and office equipment.

Semiconductor devices exploit the electrical properties of semiconductormaterials. The atomic structure of semiconductor material allows itselectrical conductivity to be manipulated by the application of anelectric field or base current or through the process of doping. Dopingintroduces impurities into the semiconductor material to manipulate andcontrol the conductivity of the semiconductor device.

A semiconductor device contains active and passive electricalstructures. Active structures, including bipolar and field effecttransistors, control the flow of electrical current. By varying levelsof doping and application of an electric field or base current, thetransistor either promotes or restricts the flow of electrical current.Passive structures, including resistors, capacitors, and inductors,create a relationship between voltage and current necessary to perform avariety of electrical functions. The passive and active structures areelectrically connected to form circuits, which enable the semiconductordevice to perform high-speed calculations and other useful functions.

Semiconductor devices are generally manufactured using two complexmanufacturing processes, i.e., front-end manufacturing, and back-endmanufacturing, each involving potentially hundreds of steps. Front-endmanufacturing involves the formation of a plurality of die on thesurface of a semiconductor wafer. Each die is typically identical andcontains circuits formed by electrically connecting active and passivecomponents. Back-end manufacturing involves singulating individual diefrom the finished wafer and packaging the die to provide structuralsupport and environmental isolation.

One goal of semiconductor manufacturing is to produce smallersemiconductor devices. Smaller devices typically consume less power,have higher performance, and can be produced more efficiently. Inaddition, smaller semiconductor devices have a smaller footprint, whichis desirable for smaller end products. A smaller die size may beachieved by improvements in the front-end process resulting in die withsmaller, higher density active and passive components. Back-endprocesses may result in semiconductor device packages with a smallerfootprint by improvements in electrical interconnection and packagingmaterials.

FIG. 1 a shows a conventional semiconductor wafer 10 with a plurality ofsemiconductor die 12 formed on substrate 11 and separated by saw street14 and wafer edge 16. Contact pads 18 and dielectric layer 20 are formedover active surface 22 of semiconductor die 12. A passivation layer 24is formed over dielectric layer 20. However, saw street 14 designatedfor singulation and wafer edge 16 are devoid of passivation. FIG. lbshows a top view of passivation layer 24 absent over saw street 14 andwafer edge 16. A redistribution layer (RDL) 28 is formed overpassivation layer 24 to extend the electrical connectivity of contactpads 18. A passivation layer 30 is formed over passivation layer 24 andRDL 28. Bumps 32 are formed at least partially over molding area 34 andelectrically connected to RDL 28. The edge pads in a fan-out wafer levelchip scale package (FO-WLCSP) tend to have unstable contact resistance,particularly when formed in PVD. In addition, out-gassing from moldingarea 34 of the FO-WLCSP in PVD is known to effect plasma stability inoxide etching.

SUMMARY OF THE INVENTION

A need exists for a stable contact resistance and plasma during oxideetching in a FO-WLCSP. Accordingly, in one embodiment, the presentinvention is a method of making a semiconductor device comprising thesteps of providing a temporary carrier, mounting a plurality ofsemiconductor die with contact pads oriented to the temporary carrier,and depositing an encapsulant over the semiconductor die and temporarycarrier. A portion of the encapsulant is designated as a saw streetbetween the semiconductor die, and a portion of the encapsulant isdesignated as a substrate edge around a perimeter of the encapsulant.The method further includes the steps of removing the temporary carrier,forming a first insulating layer over the semiconductor die, saw street,and substrate edge, forming a first conductive layer over the firstinsulating layer and electrically connected to the contact pads, forminga second insulating layer over the first conductive layer and firstinsulating layer, and singulating the encapsulant through the firstinsulating layer and saw street to separate the semiconductor die.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a carrier,mounting semiconductor die to the carrier, and depositing an encapsulantover the semiconductor die and carrier. A portion of the encapsulant isdesignated as a saw street between the semiconductor die. The methodfurther includes the steps of removing the carrier, forming a firstinsulating layer over the semiconductor die and saw street, forming afirst conductive layer over the first insulating layer, forming a secondinsulating layer over the first conductive layer and first insulatinglayer, and singulating the encapsulant through the first insulatinglayer and saw street into the semiconductor die.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a plurality ofsemiconductor die, and depositing an encapsulant over the semiconductordie. A portion of the encapsulant is designated as a saw street betweenthe semiconductor die. The method further includes the steps of forminga first insulating layer over the semiconductor die and saw street,forming an RDL over the first insulating layer, and singulating theencapsulant through the first insulating layer and saw street into thesemiconductor die.

In another embodiment, the present invention is a semiconductor devicecomprising a plurality of semiconductor die and encapsulant depositedover the semiconductor die. A portion of the encapsulant is designatedas a saw street between the semiconductor die. A first insulating layeris formed over the semiconductor die and saw street. A first conductivelayer is formed over the first insulating layer. A second insulatinglayer is formed over the first conductive layer and first insulatinglayer. The encapsulant is singulated through the first insulating layerand saw street into the semiconductor die.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-1 b illustrate a conventional semiconductor wafer with nopassivation over saw street or wafer edge;

FIG. 2 illustrates a PCB with different types of packages mounted to itssurface;

FIGS. 3 a-3 c illustrate further detail of the representativesemiconductor packages mounted to the PCB;

FIGS. 4 a-4 h illustrate a process of forming an insulating layer overthe saw street and around the substrate edge;

FIG. 5 illustrates the FO-WLCSP with an insulating layer formed over thesaw street and around the substrate edge;

FIGS. 6 a-6 d illustrate an insulating layer in a net pattern over thesaw street and around the substrate edge; and

FIGS. 7 a-7 c illustrate an insulating layer fully over the saw streetand around the substrate edge.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

Semiconductor devices are generally manufactured using two complexmanufacturing processes: front-end manufacturing and back-endmanufacturing. Front-end manufacturing involves the formation of aplurality of die on the surface of a semiconductor wafer. Each die onthe wafer contains active and passive electrical components, which areelectrically connected to form functional electrical circuits. Activeelectrical components, such as transistors and diodes, have the abilityto control the flow of electrical current. Passive electricalcomponents, such as capacitors, inductors, resistors, and transformers,create a relationship between voltage and current necessary to performelectrical circuit functions.

Passive and active components are formed over the surface of thesemiconductor wafer by a series of process steps including doping,deposition, photolithography, etching, and planarization. Dopingintroduces impurities into the semiconductor material by techniques suchas ion implantation or thermal diffusion. The doping process modifiesthe electrical conductivity of semiconductor material in active devices,transforming the semiconductor material into an insulator, conductor, ordynamically changing the semiconductor material conductivity in responseto an electric field or base current. Transistors contain regions ofvarying types and degrees of doping arranged as necessary to enable thetransistor to promote or restrict the flow of electrical current uponthe application of the electric field or base current.

Active and passive components are formed by layers of materials withdifferent electrical properties. The layers can be formed by a varietyof deposition techniques determined in part by the type of materialbeing deposited. For example, thin film deposition may involve chemicalvapor deposition (CVD), physical vapor deposition (PVD), electrolyticplating, and electroless plating processes. Each layer is generallypatterned to form portions of active components, passive components, orelectrical connections between components.

The layers can be patterned using photolithography, which involves thedeposition of light sensitive material, e.g., photoresist, over thelayer to be patterned. A pattern is transferred from a photomask to thephotoresist using light. The portion of the photoresist patternsubjected to light is removed using a solvent, exposing portions of theunderlying layer to be patterned. The remainder of the photoresist isremoved, leaving behind a patterned layer. Alternatively, some types ofmaterials are patterned by directly depositing the material into theareas or voids formed by a previous deposition/etch process usingtechniques such as electroless and electrolytic plating.

Depositing a thin film of material over an existing pattern canexaggerate the underlying pattern and create a non-uniformly flatsurface. A uniformly flat surface is required to produce smaller andmore densely packed active and passive components. Planarization can beused to remove material from the surface of the wafer and produce auniformly flat surface. Planarization involves polishing the surface ofthe wafer with a polishing pad. An abrasive material and corrosivechemical are added to the surface of the wafer during polishing. Thecombined mechanical action of the abrasive and corrosive action of thechemical removes any irregular topography, resulting in a uniformly flatsurface.

Back-end manufacturing refers to cutting or singulating the finishedwafer into the individual die and then packaging the die for structuralsupport and environmental isolation. To singulate the die, the wafer isscored and broken along non-functional regions of the wafer called sawstreets or scribes. The wafer is singulated using a laser cutting toolor saw blade. After singulation, the individual die are mounted to apackage substrate that includes pins or contact pads for interconnectionwith other system components. Contact pads formed over the semiconductordie are then connected to contact pads within the package. Theelectrical connections can be made with solder bumps, stud bumps,conductive paste, or wirebonds. An encapsulant or other molding materialis deposited over the package to provide physical support and electricalisolation. The finished package is then inserted into an electricalsystem and the functionality of the semiconductor device is madeavailable to the other system components.

FIG. 2 illustrates electronic device 50 having a chip carrier substrateor printed circuit board (PCB) 52 with a plurality of semiconductorpackages mounted on its surface. Electronic device 50 may have one typeof semiconductor package, or multiple types of semiconductor packages,depending on the application. The different types of semiconductorpackages are shown in FIG. 2 for purposes of illustration.

Electronic device 50 may be a stand-alone system that uses thesemiconductor packages to perform one or more electrical functions.Alternatively, electronic device 50 may be a subcomponent of a largersystem. For example, electronic device 50 may be a graphics card,network interface card, or other signal processing card that can beinserted into a computer. The semiconductor package can includemicroprocessors, memories, application specific integrated circuits(ASIC), logic circuits, analog circuits, RF circuits, discrete devices,or other semiconductor die or electrical components.

In FIG. 2, PCB 52 provides a general substrate for structural supportand electrical interconnect of the semiconductor packages mounted on thePCB. Conductive signal traces 54 are formed over a surface or withinlayers of PCB 52 using evaporation, electrolytic plating, electrolessplating, screen printing, or other suitable metal deposition process.Signal traces 54 provide for electrical communication between each ofthe semiconductor packages, mounted components, and other externalsystem components. Traces 54 also provide power and ground connectionsto each of the semiconductor packages.

In some embodiments, a semiconductor device has two packaging levels.First level packaging is a technique for mechanically and electricallyattaching the semiconductor die to an intermediate carrier. Second levelpackaging involves mechanically and electrically attaching theintermediate carrier to the PCB. In other embodiments, a semiconductordevice may only have the first level packaging where the die ismechanically and electrically mounted directly to the PCB.

For the purpose of illustration, several types of first level packaging,including wire bond package 56 and flip chip 58, are shown on PCB 52.Additionally, several types of second level packaging, including ballgrid array (BGA) 60, bump chip carrier (BCC) 62, dual in-line package(DIP) 64, land grid array (LGA) 66, multi-chip module (MCM) 68, quadflat non-leaded package (QFN) 70, and quad flat package 72, are shownmounted on PCB 52. Depending upon the system requirements, anycombination of semiconductor packages, configured with any combinationof first and second level packaging styles, as well as other electroniccomponents, can be connected to PCB 52. In some embodiments, electronicdevice 50 includes a single attached semiconductor package, while otherembodiments call for multiple interconnected packages. By combining oneor more semiconductor packages over a single substrate, manufacturerscan incorporate pre-made components into electronic devices and systems.Because the semiconductor packages include sophisticated functionality,electronic devices can be manufactured using cheaper components and astreamlined manufacturing process. The resulting devices are less likelyto fail and less expensive to manufacture resulting in a lower cost forconsumers.

FIGS. 3 a-3 c show exemplary semiconductor packages. FIG. 3 aillustrates further detail of DIP 64 mounted on PCB 52. Semiconductordie 74 includes an active region containing analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed within the die and are electricallyinterconnected according to the electrical design of the die. Forexample, the circuit may include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements formedwithin the active region of semiconductor die 74. Contact pads 76 areone or more layers of conductive material, such as aluminum (Al), copper(Cu), tin (Sn), nickel (Ni), gold (Au), or silver (Ag), and areelectrically connected to the circuit elements formed withinsemiconductor die 74. During assembly of DIP 64, semiconductor die 74 ismounted to an intermediate carrier 78 using a gold-silicon eutecticlayer or adhesive material such as thermal epoxy or epoxy resin. Thepackage body includes an insulative packaging material such as polymeror ceramic. Conductor leads 80 and wire bonds 82 provide electricalinterconnect between semiconductor die 74 and PCB 52. Encapsulant 84 isdeposited over the package for environmental protection by preventingmoisture and particles from entering the package and contaminating die74 or wire bonds 82.

FIG. 3 b illustrates further detail of BCC 62 mounted on PCB 52.Semiconductor die 88 is mounted over carrier 90 using an underfill orepoxy-resin adhesive material 92. Wire bonds 94 provide first levelpackaging interconnect between contact pads 96 and 98. Molding compoundor encapsulant 100 is deposited over semiconductor die 88 and wire bonds94 to provide physical support and electrical isolation for the device.Contact pads 102 are formed over a surface of PCB 52 using a suitablemetal deposition process such as electrolytic plating or electrolessplating to prevent oxidation. Contact pads 102 are electricallyconnected to one or more conductive signal traces 54 in PCB 52. Bumps104 are formed between contact pads 98 of BCC 62 and contact pads 102 ofPCB 52.

In FIG. 3 c, semiconductor die 58 is mounted face down to intermediatecarrier 106 with a flip chip style first level packaging. Active region108 of semiconductor die 58 contains analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed according to the electrical design of the die.For example, the circuit may include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements withinactive region 108. Semiconductor die 58 is electrically and mechanicallyconnected to carrier 106 through bumps 110.

BGA 60 is electrically and mechanically connected to PCB 52 with a BGAstyle second level packaging using bumps 112. Semiconductor die 58 iselectrically connected to conductive signal traces 54 in PCB 52 throughbumps 110, signal lines 114, and bumps 112. A molding compound orencapsulant 116 is deposited over semiconductor die 58 and carrier 106to provide physical support and electrical isolation for the device. Theflip chip semiconductor device provides a short electrical conductionpath from the active devices on semiconductor die 58 to conductiontracks on PCB 52 in order to reduce signal propagation distance, lowercapacitance, and improve overall circuit performance. In anotherembodiment, the semiconductor die 58 can be mechanically andelectrically connected directly to PCB 52 using flip chip style firstlevel packaging without intermediate carrier 106.

FIGS. 4 a-4 h illustrate, in relation to FIGS. 2 and 3 a-3 c, a processof forming an insulating layer over the saw street and around thesubstrate edge. In FIG. 4 a, a substrate or carrier 120 containstemporary or sacrificial base material such as silicon, polymer, polymercomposite, metal, ceramic, glass, glass epoxy, beryllium oxide, or othersuitable low-cost, rigid material for structural support. An interfacelayer or tape 122 is applied over carrier 120 as a temporary adhesive orbonding layer releasable with ultra-violet (UV) light or heat.

Semiconductor die 124 are mounted to adhesive tape 122 with contact pads126 and active surface 128 oriented toward carrier 120. Active surface128 contains analog or digital circuits implemented as active devices,passive devices, conductive layers, and dielectric layers formed withinthe die and electrically interconnected according to the electricaldesign and function of the die. For example, the circuit may include oneor more transistors, diodes, and other circuit elements formed withinactive surface 128 to implement analog circuits or digital circuits,such as digital signal processor (DSP), ASIC, memory, or other signalprocessing circuit. Semiconductor die 124 may also contain IPDs, such asinductors, capacitors, and resistors, for RF signal processing.

An insulating or dielectric layer 130 is formed over active surface 128and contact pads 126 using PVD, CVD, printing, spin coating, spraycoating, or thermal oxidation. The insulating layer 130 can be one ormore layers of silicon dioxide (SiO2), silicon nitride (Si3N4), siliconoxynitride (SiON), tantalum pentoxide (Ta2O5), aluminum oxide (Al2O3),polyimide, benzocyclobutene (BCB), polybenzoxazoles (PBO), or othersuitable dielectric material. A portion of insulating layer 130 isremoved by an etching process to expose contact pads 126.

FIG. 4 b shows semiconductor die 124 mounted to adhesive tape 122. Anencapsulant or molding compound 132 is deposited over carrier 120 andsemiconductor die 124 using a paste printing, compressive molding,transfer molding, liquid encapsulant molding, vacuum lamination, spincoating, or other suitable applicator. Encapsulant 132 can be polymercomposite material, such as epoxy resin with filler, epoxy acrylate withfiller, or polymer with proper filler. Encapsulant 132 is non-conductiveand environmentally protects the semiconductor device from externalelements and contaminants.

In FIG. 4 c, carrier 120 and adhesive tape 122 are removed by chemicaletching, mechanical peel-off, CMP, mechanical grinding, thermal bake,laser scanning, wet stripping, UV light, or heat. Semiconductor die 124remain embedded with encapsulant 132 which operates as substrate 133with embedded or caved die. Saw street 134 defines an area for latersingulation operation. Substrate edge 135 defines a perimeter of thesubstrate.

In FIG. 4 d, an insulating or passivation layer 136 is formed oversubstrate 133 by PVD, CVD, printing, spin coating, spray coating, orthermal oxidation. The insulating layer 136 can be one or more layers ofSiO2, Si3N4, SiON, Ta2O5, Al2O3, or other material having similarinsulating and structural properties. In particular, insulating layer136 a covers contact pads 126, insulating layer 130, and molding area138 designated for interconnect fan-out. A portion of insulating layer136 a is removed by an etching process to expose contact pads 126. Theetching process also creates a gap or channel 140 in the insulatinglayer on opposing sides of saw street 134 which defines insulating layer136 b over the saw region designated for singulation. Channel 140further defines insulating layer 136 c along substrate edge 135.

FIG. 4 e is a top view of insulating layer 136 over substrate 133. Inone embodiment, channel 140 is 10-30 micrometers wide. The insulatinglayer 136 b and 136 c partially covers saw street 134 and substrate edge135. Channel 140 extends to the package passivation edge to minimize thefront side outgassing from molding surface 138. The insulating layer 136also planarizes the surface for subsequent layers and secures thethickness of final passivation over contact pads 126 for bumping, whichin turn controls the reliability of singulated die on a test board,particularly for corner bumps.

In FIG. 4 f, an electrically conductive layer 142 is formed overinsulating layer 136 a and contact pads 126 using patterning and PVD,CVD, electrolytic plating, electroless plating process, or othersuitable metal deposition process. Conductive layer 142 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 142 is electrically connected tocontact pads 126 and operates as an RDL to extend the electricalconnectivity of the contact pads. Additional RDL layers can be built upon the substrate.

An insulating or passivation layer 144 is formed over insulating layer136 a and RDL 142 by PVD, CVD, printing, spin coating, spray coating, orthermal oxidation. The insulating layer 144 can be one or more layers ofSiO2, Si3N4, SiON, Ta2O5, Al2O3, or other material having similarinsulating and structural properties. A portion of insulating layer 144is removed by an etching process to expose RDL 142.

In FIG. 4 g, an electrically conductive bump material is deposited overRDL 142 using an evaporation, electrolytic plating, electroless plating,ball drop, or screen printing process. The bump material can be Al, Sn,Ni, Au, Ag, Pb, Bi, Cu, solder, and combinations thereof, with anoptional flux solution. For example, the bump material can be eutecticSn/Pb, high-lead solder, or lead-free solder. The bump material isbonded to RDL 142 using a suitable attachment or bonding process. In oneembodiment, the bump material is reflowed by heating the material aboveits melting point to form spherical balls or bumps 146 extending atleast partially over molding area 138. In some applications, bumps 146are reflowed a second time to improve electrical contact to RDL 142. Thebumps can also be compression bonded to RDL 142. Bumps 146 represent onetype of interconnect structure that can be formed over RDL 142. Theinterconnect structure can also use bond wires, stud bump, micro bump,or other electrical interconnect.

In FIG. 4 h, substrate 133 is singulated through insulating layer 136and saw street 134 using saw blade or laser cutting tool 148 to separatethe individual semiconductor die 124 into FO-WLCSP 150. Saw blade orlaser cutting tool 148 can use a single cut or step cut.

FIG. 5 shows FO-WLCSP 150 after singulation. Contact pads 132, RDL 142,and bumps 146 provide electrical connection to the circuits on activesurface 130. The insulating layer 136 is formed prior to RDL 142 andcovers saw street 134 and substrate edge 135, less channel 140, toreduce out-gassing from molding area 138. The insulating layer 136improves contact resistance in PVD for fan-out edge pads and plasmastability during oxide etching. The insulating layer 136 also reducesparticles and other contaminants from molding area 138 duringsingulation.

FIGS. 6 a-6 d illustrate, in relation to FIGS. 2 and 3 a-3 c, a processof forming an insulating layer in a net pattern over the saw street andaround the substrate edge. FIG. 6 a shows substrate 160 with embeddedsemiconductor die 164, similar to FIG. 4 c. Semiconductor die 164 haveactive surface 170 containing analog or digital circuits implemented asactive devices, passive devices, conductive layers, and dielectriclayers formed within the die and electrically interconnected accordingto the electrical design and function of the die. For example, thecircuit may include one or more transistors, diodes, and other circuitelements formed within active surface 170 to implement analog circuitsor digital circuits, such as DSP, ASIC, memory, or other signalprocessing circuit. Semiconductor die 164 may also contain IPDs, such asinductors, capacitors, and resistors, for RF signal processing.

An insulating or dielectric layer 174 is formed over active surface 170and contact pads 172 using PVD, CVD, printing, spin coating, spraycoating, or thermal oxidation. The insulating layer 174 can be one ormore layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, polyimide, BCB, PBO, orother suitable dielectric material. A portion of insulating layer 174 isremoved by an etching process to expose contact pads 172.

An insulating or passivation layer 176 is formed in a net pattern oversemiconductor wafer 160 by PVD, CVD, printing, spin coating, spraycoating, or thermal oxidation. The insulating layer 176 can be one ormore layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, or other material havingsimilar insulating and structural properties. In particular, insulatinglayer 176 a covers contact pads 172, insulating layer 174, and moldingarea 178 designated for interconnect fan-out. A portion of insulatinglayer 176 a is removed by an etching process to expose contact pads 172.The etching process also creates net pattern 180 in the insulating layeron either side of saw street 166 which defines insulating layer 176 bover saw street 166 designated for singulation. Net pattern 180 furtherdefines insulating layer 176 c along substrate edge 168. FIG. 6 b is atop view of insulating layer 176 with a net pattern 180 oversemiconductor wafer 160. In net pattern 180, some portions of insulatinglayer 176 extend between insulating layer 176 a, and other portions ofinsulating layer 176 are broken by the net pattern. FIG. 6 c showsfurther detail of net pattern 180 with alternating pattern of presenceand absence of insulating layer 176. The insulating layer 176 b and 176c, with net pattern 180, reduces out-gassing from molding area 178.

Returning to FIG. 6 a, an electrically conductive layer 182 is formedover insulating layer 176 a and contact pads 172 using patterning andPVD, CVD, electrolytic plating, electroless plating process, or othersuitable metal deposition process. Conductive layer 182 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 182 is electrically connected tocontact pads 172 and operates as an RDL to extend the electricalconnectivity of the contact pads.

An insulating or passivation layer 184 is formed over insulating layer176 a and RDL 182 by PVD, CVD, printing, spin coating, spray coating, orthermal oxidation. The insulating layer 184 can be one or more layers ofSiO2, Si3N4, SiON, Ta2O5, Al2O3, or other material having similarinsulating and structural properties. A portion of insulating layer 184is removed by an etching process to expose RDL 182.

An electrically conductive bump material is deposited over RDL 182 usingan evaporation, electrolytic plating, electroless plating, ball drop, orscreen printing process. The bump material can be Al, Sn, Ni, Au, Ag,Pb, Bi, Cu, solder, and combinations thereof, with an optional fluxsolution. For example, the bump material can be eutectic Sn/Pb,high-lead solder, or lead-free solder. The bump material is bonded toRDL 182 using a suitable attachment or bonding process. In oneembodiment, the bump material is reflowed by heating the material aboveits melting point to form spherical balls or bumps 186 extending atleast partially over molding area 178. In some applications, bumps 186are reflowed a second time to improve electrical contact to RDL 182. Thebumps can also be compression bonded to RDL 182. Bumps 186 represent onetype of interconnect structure that can be formed over RDL 182. Theinterconnect structure can also use bond wires, stud bump, micro bump,or other electrical interconnect.

In FIG. 6 d, semiconductor wafer 160 is singulated through insulatinglayer 176 and saw street 166 using saw blade or laser cutting tool 188to separate the individual semiconductor die 164 into FO-WLCSP 190,similar to FIG. 5. Saw blade or laser cutting tool 188 can use a singlecut or step cut. Contact pads 172, RDL 182, and bumps 186 provideelectrical connection to the circuits on active surface 170. Theinsulating layer 176 is formed prior to RDL 182 and covers saw street166 and substrate edge 168, less net pattern 180, to reduce out-gassingfrom molding area 178. The insulating layer 176 improves contactresistance in PVD for fan-out edge pads and plasma stability duringoxide etching. The insulating layer 176 also reduces particles and othercontaminants from molding area 178 during singulation.

FIGS. 7 a-7 c illustrate, in relation to FIGS. 2 and 3 a-3 c, a processof forming an insulating layer with full coverage over the saw streetand around the substrate edge. FIG. 7 a shows substrate 200 withembedded semiconductor die 204, similar to FIG. 4 c. Semiconductor die204 have an active surface 210 containing analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed within the die and electrically interconnectedaccording to the electrical design and function of the die. For example,the circuit may include one or more transistors, diodes, and othercircuit elements formed within active surface 210 to implement analogcircuits or digital circuits, such as DSP, ASIC, memory, or other signalprocessing circuit. Semiconductor die 164 may also contain IPDs, such asinductors, capacitors, and resistors, for RF signal processing.

An electrically conductive layer 212 is formed over active surface 210using patterning and PVD, CVD, electrolytic plating, electroless platingprocess, or other suitable metal deposition process. Conductive layer212 can be one or more layers of Al, Cu, Sn, Ni, Au, Ag, or othersuitable electrically conductive material. Conductive layer 212 operatesas contact pads electrically connected to the circuits on active surface210.

An insulating or dielectric layer 214 is formed over active surface 210and contact pads 212 using PVD, CVD, printing, spin coating, spraycoating, or thermal oxidation. The insulating layer 214 can be one ormore layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, polyimide, BCB, PBO, orother suitable dielectric material. A portion of insulating layer 214 isremoved by an etching process to expose contact pads 212.

An insulating or passivation layer 216 is formed with full coverage oversemiconductor wafer 200 by PVD, CVD, printing, spin coating, spraycoating, or thermal oxidation.

The insulating layer 216 can be one or more layers of SiO2, Si3N4, SiON,Ta2O5, Al2O3, or other material having similar insulating and structuralproperties. In particular, insulating layer 216 covers contact pads 212,insulating layer 214, molding area 218, substrate edge 208, and sawstreet 206 designated for interconnect fan-out. A portion of insulatinglayer 216 is removed by an etching process to expose contact pads 212.FIG. 7 b is a top view of insulating layer 216 fully coveringsemiconductor wafer 200, including molding area 218, saw street 206, andsubstrate edge 208.

An electrically conductive layer 222 is formed over insulating layer 216and contact pads 212 using patterning and PVD, CVD, electrolyticplating, electroless plating process, or other suitable metal depositionprocess. Conductive layer 222 can be one or more layers of Al, Cu, Sn,Ni, Au, Ag, or other suitable electrically conductive material.Conductive layer 222 is electrically connected to contact pads 212 andoperates as an RDL to extend the electrical connectivity of the contactpads.

An insulating or passivation layer 224 is formed over insulating layer216 and RDL 222 by PVD, CVD, printing, spin coating, spray coating, orthermal oxidation. The insulating layer 224 can be one or more layers ofSiO2, Si3N4, SiON, Ta2O5, Al2O3, or other material having similarinsulating and structural properties. A portion of insulating layer 224is removed by an etching process to expose RDL 222.

An electrically conductive bump material is deposited over RDL 222 usingan evaporation, electrolytic plating, electroless plating, ball drop, orscreen printing process. The bump material can be Al, Sn, Ni, Au, Ag,Pb, Bi, Cu, solder, and combinations thereof, with an optional fluxsolution. For example, the bump material can be eutectic Sn/Pb,high-lead solder, or lead-free solder. The bump material is bonded toRDL 222 using a suitable attachment or bonding process. In oneembodiment, the bump material is reflowed by heating the material aboveits melting point to form spherical balls or bumps 226 extending atleast partially over molding area 218. In some applications, bumps 226are reflowed a second time to improve electrical contact to RDL 222. Thebumps can also be compression bonded to RDL 222. Bumps 226 represent onetype of interconnect structure that can be formed over RDL 222. Theinterconnect structure can also use bond wires, stud bump, micro bump,or other electrical interconnect.

In FIG. 7 c, semiconductor wafer 200 is singulated through insulatinglayer 216 and saw street 206 using saw blade or laser cutting tool 228to separate the individual semiconductor die 204 into FO-WLCSP 230,similar to FIG. 5. Saw blade or laser cutting tool 228 can use a singlecut or step cut. Contact pads 212, RDL 222, and bumps 226 provideelectrical connection to the circuits on active surface 210. Theinsulating layer 216 is formed prior to RDL 222 and fully covers sawstreet 206 and substrate edge 208. The insulating layer 216 improvescontact resistance in PVD for fan-out edge pads and plasma stabilityduring oxide etching. The insulating layer 216 also reduces particlesand other contaminants from molding area 218 during singulation.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

What is claimed:
 1. A method of manufacturing a semiconductor device,comprising: providing a carrier; mounting a plurality of semiconductordie with contact pads oriented to the carrier; depositing an encapsulantover the semiconductor die and carrier, wherein a portion of theencapsulant is designated as a saw street between the semiconductor dieand a portion of the encapsulant is designated as a substrate edgearound a perimeter of the encapsulant; removing the carrier to expose asurface of the encapsulant; forming a first insulating layer over thesemiconductor die and directly on the saw street and substrate edge;forming a conductive layer over the first insulating layer andcontacting the semiconductor die; forming a second insulating layer overthe conductive layer and first insulating layer; and singulating theencapsulant through the first insulating layer and saw street toseparate the semiconductor die.
 2. The method of claim 1, furtherincluding forming the first insulating layer to cover a molding areaaround the semiconductor die.
 3. The method of claim 2, furtherincluding forming the first insulating layer to cover the entire sawstreet and molding area.
 4. The method of claim 1, further includingforming a channel in the first insulating layer on opposing sides of thesaw street.
 5. The method of claim 1, further including forming achannel in the first insulating layer along the substrate edge.
 6. Themethod of claim 1, further including forming the first insulating layerin a net pattern to cover the saw street and substrate edge.
 7. Themethod of claim 1, further including forming a bump over the conductivelayer.
 8. A method of manufacturing a semiconductor device, comprising:providing a carrier; mounting semiconductor die to the carrier;depositing an encapsulant over the semiconductor die and carrier,wherein a portion of the encapsulant is designated as a saw streetbetween the semiconductor die; removing the carrier to expose a surfaceof the encapsulant; forming a first insulating layer over thesemiconductor die and directly on the saw street; forming a conductivelayer on the semiconductor die and over the first insulating layer;forming a second insulating layer over the conductive layer and firstinsulating layer; and singulating the encapsulant through the firstinsulating layer and saw street.
 9. The method of claim 8, wherein aportion of the encapsulant is designated as a substrate edge around aperimeter of the encapsulant.
 10. The method of claim 9, furtherincluding forming a channel in the first insulating layer along thesubstrate edge.
 11. The method of claim 9, further including forming thefirst insulating layer in a net pattern to cover the saw street andsubstrate edge.
 12. The method of claim 8, further including forming thefirst insulating layer to cover a molding area around the semiconductordie.
 13. The method of claim 12, further including forming the firstinsulating layer to cover the entire saw street and molding area. 14.The method of claim 8, further including forming a channel in the firstinsulating layer on opposing sides of the saw street.
 15. A method ofmanufacturing a semiconductor device, comprising: providing a pluralityof semiconductor die; depositing an encapsulant over the semiconductordie, wherein a portion of the encapsulant is designated as a saw streetbetween the semiconductor die; forming an insulating layer over thesemiconductor die and directly on the encapsulant; forming aredistribution layer (RDL) over the insulating layer; and singulatingthe encapsulant through the insulating layer and saw street.
 16. Themethod of claim 15, wherein a portion of the encapsulant is designatedas a substrate edge around a perimeter of the encapsulant.
 17. Themethod of claim 16, further including forming a channel in theinsulating layer along the substrate edge.
 18. The method of claim 16,further including forming the insulating layer in a net pattern to coverthe saw street and substrate edge.
 19. The method of claim 15, furtherincluding forming the insulating layer to cover the entire saw streetand a molding area around the semiconductor die.
 20. The method of claim15, further including forming a channel in the insulating layer onopposing sides of the saw street.
 21. A method of manufacturing asemiconductor device, comprising: providing a plurality of semiconductordie; depositing an encapsulant around the semiconductor die; forming aninsulating layer directly on and in contact with the encapsulant;forming a conductive layer over the insulating layer; and singulatingthe encapsulant through the insulating layer.
 22. The method of claim21, further including: forming a first channel in the insulating layer;forming a second channel in the insulating layer; and singulating theencapsulant through the insulating layer between the first and secondchannels in the insulating layer.
 23. The method of claim 21, furtherincluding: forming a first net pattern in the insulating layer; forminga second net pattern in the insulating layer; and singulating theencapsulant through the insulating layer between the first and secondnet patterns in the insulating layer.
 24. The method of claim 21,further including singulating the encapsulant using a step cut.